Welcome to this deck on averages and spread. In statistics, we often want to summarise a set of data with just a couple of numbers. We use an 'average' to find a typical value, and a measure of 'spread' to see how consistent or spread out the data is. We'll cover the three main averages: the mean, median, and mode, and two measures of spread: the range and the interquartile range.

Let's start with the simplest average: the mode. The mode is simply the value that appears most often in a set of data. Think of 'mode' and 'most' - they both start the same way. For example, in the list of numbers 5, 2, 5, 8, the number 5 appears twice, more than any other number. So, the mode is 5.

A set of data can sometimes have more than one mode. If two values appear with the same highest frequency, we say the data is bimodal. If no number appears more than any other, then there is no mode.